// highp -2^16 - 2^16
// mediump -2^10 - 2^10
// lowp -2^8 - 2^8
precision lowp float; // 指定精度
varying vec2 v_uv; // 接收顶点着色器传入的数据
void main(){
    // gl_FragColor = vec4(1.0,0.4,0.0,1.0);
    gl_FragColor = vec4(v_uv,0.0,1.0);
}